Drilling‐induced isothermal remanent magnetization

Geophysics ◽  
1990 ◽  
Vol 55 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Michael J. Pinto ◽  
Michael McWilliams
Keyword(s):  
Remanent Magnetization ◽  
Mineral Exploration ◽  
Petroleum Exploration ◽  
Isothermal Remanent Magnetization ◽  
Scientific Drilling ◽  
Core Samples ◽  
Considerable Success

The recovery of core samples is important in petroleum exploration, mineral exploration, and scientific drilling projects; and often complete orientation of the samples (azimuth and plunge) is desirable. Recovered cores are usually not azimuthally oriented because of the costs associated with deployment and operation of downhole orientation tools. Inexpensive paleomagnetic orientation methods have been used with considerable success in the borehole environment (Van der Voo and Watts, 1978; Kodama, 1984; Bleakly et al., 1985a, b; Evans and Mailol, 1986; Layer et al., 1988; McWilliams and Pinto, 1988). In some cases, the technique has been hampered by secondary magnetizations associated with the drillstring and/or coring tool, magnetizations which have partially or completely overprinted the primary and secondary magnetizations used for orientation.

IRMITS: A MATLAB program for analyzing isothermal remanent magnetization (IRM) data

2020 ◽  
Author(s):  
Adika Bagaskara ◽  
Christopher Salim ◽  
Muhammad Archie Antareza ◽  
Kevin Dwimanggala Tjiongnotoputera ◽  
Mariyanto Mariyanto
Keyword(s):  
Remanent Magnetization ◽  
Isothermal Remanent Magnetization ◽  
Matlab Program

Evidence of Single-Domain Magnetite in the Michikamau Anorthosite

1971 ◽  
Vol 8 (3) ◽  
pp. 361-370 ◽  
Author(s):  
G. S. Murthy ◽  
M. E. Evans ◽  
D. I. Gough
Keyword(s):  
Remanent Magnetization ◽  
Theoretical Models ◽  
Natural Remanent Magnetization ◽  
Single Domain ◽  
Isothermal Remanent Magnetization ◽  
Mineral Separation ◽  
Domain Configuration ◽  
Plagioclase Felspar ◽  
Magnetite Particles ◽  
Theoretical Evidence

The Michikamau anorthosite possesses very stable natural remanent magnetization, some of which resists alternating fields up to 1800 Oe. The rock contains two types of opaque grains, fine opaque needles of order 10 × 0.5 μ in the plagioclase felspar, and large equidimensional magnetite particles. Ore microscope studies suggest, but do not establish, that the needles are composed of magnetite. Saturation isothermal remanence and thermal demagnetization studies indicate magnetite as the carrier of remanent magnetization. In order to distinguish the effects of the large grains from those of the needles, mineral separation was used to show that an artificial specimen of essentially pure plagioclase had very similar isothermal remanent magnetization properties to the whole rock. Both indicated magnetite as the magnetic mineral. Thermoremanent properties of the separated mineral fractions indicated magnetite as the dominant magnetic constituent but showed some evidence of laboratory-produced hematite. Theoretical models of grains elongated along [111] and [110] axes are used to show that magnetite needles can exist in stable single-domain configuration in the size and shape ranges of the needles observed in the Michikamau anorthosite. There is thus considerable experimental and theoretical evidence for the conclusion that the stable remanent magnetization of the Michikamau anorthosite is carried by fine single–domain needles of magnetite in the plagioclase felspar.

Effect of Drill-Ship Motions on Core Sample Conditions During the Nankai Trough Seismogenic Zone Experiment

2009 ◽  
Author(s):  
Yuichi Shinmoto ◽  
Kazuyasu Wada
Keyword(s):  
Deep Sea ◽  
Nankai Trough ◽  
Drill String ◽  
Seismogenic Zone ◽  
Ship Motions ◽  
Scientific Drilling ◽  
Core Samples ◽  
Core Recovery ◽  
Drilling Parameters ◽  
Core Conditions

The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) Stage 1A, which is a part of the Integrated Ocean Drilling Program (IODP), is a series of expeditions in scientific drilling and coring operations aboard the first riser-equipped deep sea drilling vessel, Chikyu. The objectives are to recover good quality core samples and collect data on undersea properties and drilling conditions, which will also provide valuable information for future expeditions. The coring operations were carried out under harsh drilling and ocean conditions so that core recovery was inconsistent and fluctuated from high to low. Moreover, differences in independent lithology, depth, and the type of coring tools from previous expeditions made it necessary to analyze and optimize drilling parameters with new data. A serious concern in retrieving core samples was the vertical heave motions caused by the drill-ship since the active heave compensator system could not be activated before operations due to the extreme deep sea conditions and only the passive heave compensator was used. The drill string and coring tools are particularly vulnerable to the high heaving movements of the vessel so that the core recovery rate and quality are also adversely affected. The present work presents an analysis of geotechnical information, drilling parameters and the drill-ship motions the NanTroSEIZE expedition in order to optimize core conditions and maintain high core recovery.

Photo-induced magnetic behavior in the amorphous spin-glass material Co3(SbTe3)2

1994 ◽  
Vol 9 (4) ◽  
pp. 909-914 ◽  
Author(s):  
Biao Wu ◽  
Lianwei Ren ◽  
Charles J. O'Connor ◽  
Jinke Tang ◽  
Jin-Seung Jung ◽  
...  
Keyword(s):  
Spin Glass ◽  
Remanent Magnetization ◽  
Magnetic Behavior ◽  
Freezing Temperature ◽  
Specific Resistivity ◽  
Metathesis Reaction ◽  
Isothermal Remanent Magnetization ◽  
Magnetization Data ◽  
Magnetizing Field ◽  
Thermal Remanent Magnetization

A new ternary material Co3(SbTe3)2 was prepared by using a rapid precipitation metathesis reaction between the Zintl material K3SbTe3 and CoCl2 in aqueous solution. The dc specific resistivity of this material is in the region for metallic conductors (p = 2.75 × 10-3 Ω-cm). The dc magnetic susceptibility of Co3(SbTe3)2 is reported over a 2.2 K-300 K temperature region, and the material is characterized as a spin glass with a freezing temperature of about 5 K. Magnetization data are also reported as both thermal remanent magnetization and isothermal remanent magnetization as a function of magnetizing field and temperature. When cooled well below the glass freezing temperature, the frozen spin glass has been observed to exhibit photomagnetic effects consistent with a disruption of the spin-glass state caused by uv-radiation.

Age of the Firesand River carbonatite complex from paleomagnetism

1989 ◽  
Vol 26 (11) ◽  
pp. 2401-2405 ◽  
Author(s):  
D. T. A. Symons
Keyword(s):  
Remanent Magnetization ◽  
Pole Position ◽  
Blocking Temperature ◽  
Isothermal Remanent Magnetization ◽  
Carbonatite Complex ◽  
Polar Wander ◽  
Partial Contact ◽  
Apparent Polar Wander Path ◽  
Temperature Spectra ◽  
Middle Proterozoic

The 2.3 km diameter Firesand River complex intrudes Archean volcanics and granites of the Wawa Subprovince in the Superior Province about 8 km east of Wawa, Ontario. It has given differing Middle Proterozoic K–Ar biotite ages of 1018 ± 50 and 1097 Ma. Alternating-field and thermal step demagnetization of specimens from three calcific carbonatite sites, five ferruginous dolomitic carbonatite sites, and one lamprophyre dike site isolated a stable mean direction of 290°, 33 °(α95 = 12°). Isothermal remanent magnetization tests indicate the remanence is held by single-to pseudosingle-domain magnetite and hematite in the carbonatite. The dike remanence is Keweenawan in age, thereby confirming its genetic relationship to the complex, and it gives a positive partial contact test with its host rock, indicating no postintrusive remagnetization. The blocking-temperature spectra indicate that postintrusive uplift has not exceeded about 4 km. The pole position for the complex is 183°E, 27°N (dp = 8°, dm = 13°). This pole lies directly on the well-dated Keweenawan apparent polar wander path, giving an age of 1090 ± 10 Ma, in agreement with the older K–Ar age. It also confirms geologic and aeromagnetic evidence that the complex has not been tectonically tilted since emplacement.

Magnetic characteristics of Luna 16 and 20 samples

1977 ◽  
Vol 284 (1319) ◽  
pp. 151-156 ◽  
Keyword(s):  
Grain Size ◽  
Iron Content ◽  
Remanent Magnetization ◽  
Natural Remanent Magnetization ◽  
Magnetic Behaviour ◽  
Heavy Fraction ◽  
Magnetic Characteristics ◽  
Iron Particles ◽  
Isothermal Remanent Magnetization ◽  
Rock Fragments

The natural remanent magnetization of rock fragments L2015,3,1 and L2015,3,11 was found to be < 3.5 x 10 -7 and < 40 x 10 -6 G cm 3 g -1 respectively. The former sample, from isothermal remanent magnetization (i.r.m.) measurements, contained very little iron, while the latter sample had a much higher iron content and exhibited i.r.m. characteristics similar to breccia samples from Apollo missions. Susceptibility and i.r.m. measurements have shown that Luna 16 fines contain about four times as much iron as Luna 20 samples and that the light fractions from the density separations contain about twice as much iron as the heavy fraction. Like the Apollo fines, the magnetic behaviour of Luna 16 and 20 fines is dominated by small iron particles, most of which are superparamagnetic and of grain size less than about 13 nm.

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